The development of systems capable of responding to environmental changes, such as humidity, requires the design and assembly of highly sensitive and efficiently transducing elements. Such a challenge can be mastered only by disentangling the role played by each component of the responsive system, thus ultimately achieving high performance by optimizing the synergistic contribution of all functional elements. Here, we designed and synthesized a novel [1]benzothieno [3,2-b][1]benzothiophene derivative equipped with hydrophilic oligoethylene glycol lateral chains (OEG-BTBT) that can electrically transduce subtle changes in ambient humidity with high current ratios (>10 4 ) at low voltages (2 V), reaching state-of-the-art performance. Multiscale structural, spectroscopical, and electrical characterizations were employed to elucidate the role of each device constituent, viz., the active material's BTBT core and OEG side chains, and the device interfaces. While the BTBT molecular core promotes the self-assembly of (semi)conducting crystalline films, its OEG side chains are prone to adsorb ambient moisture. These chains act as hotspots for hydrogen bonding with atmospheric water molecules that locally dissociate when a bias voltage is applied, resulting in a mixed electronic/protonic long-range conduction throughout the film. Due to the OEG-BTBT molecules' orientation with respect to the surface and structural defects within the film, water molecules can access the humidity-sensitive sites of the SiO 2 substrate surface, whose hydrophilicity can be tuned for an improved device response. The synergistic chemical engineering of materials and interfaces is thus key for designing highly sensitive humidity-responsive electrical devices whose mechanism relies on the interplay of electron and proton transport.

Phenoxazine is a heterocyclic molecule, which is used either as a parent molecule or with substituents for applications in various scientific fields: e.g., as a potential antioxidant. The purpose of this work is to present the molecular packing of phenoxazine within the crystalline state, as surprisingly no crystal structure is known so far. The crystal structure solution was performed by single-crystal X-ray investigations. Although the molecule has some potential for intermolecular hydrogen bonding, the observed structure is the classical herringbone packing typical for rodlike conjugated molecules. However, severe substitutional disorder of oxygen and nitrogen atoms is observed over their two opposite positions within the molecule. To get deeper insight into this disorder phenomenon, theoretical studies were performed, including crystal structure prediction using state of the art density functional theory techniques. The theoretical investigations confirm the experimentally observed 50% occupancy of the oxygen and nitrogen atoms.

Chiral molecules are known to behave as spin filters due to the chiral induced spin selectivity (CISS) effect. Chirality can be implemented in molecular semiconductors in order to study the role of the CISS effect in charge transport and to find new materials for spintronic applications. In this study, the design and synthesis of a new class of enantiopure chiral organic semiconductors based on the well‐known dinaphtho[2,3‐b:2,3‐f]thieno[3,2‐b]thiophene (DNTT) core functionalized with chiral alkyl side chains is presented. When introduced in an organic field‐effect transistor (OFET) with magnetic contacts, the two enantiomers, (R)‐DNTT and (S)‐DNTT, show an opposite behavior with respect to the relative direction of the magnetization of the contacts, oriented by an external magnetic field. Each enantiomer displays an unexpectedly high magnetoresistance over one preferred orientation of the spin current injected from the magnetic contacts. The result is the first reported OFET in which the current can be switched on and off upon inversion of the direction of the applied external magnetic field. This work contributes to the general understanding of the CISS effect and opens new avenues for the introduction of organic materials in spintronic devices.

The appearance of different polymorphs at surfaces is a well-known phenomenon for organic molecules. Here the molecule phenoxazine, a small molecule with a rather rigid conformation whose bulk crystal structure...

We present an experimental study of the dynamics of a well-pronounced secondary relaxation observed in bulk and ultrathin films of the fluorinated copolymer poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP). In proximity to the glass transition, an anomalous phenomenon is observed: the β-relaxation slows down upon heating. Measurements as a function of the film thickness show that this exceptional behavior gradually vanishes upon confinement at the nanoscale level. Regardless of sample size, the relaxation dynamics could be described in terms of the Minimal Model via an asymmetric double well potential. Supported by a structural investigation of surfaces and interfaces, our results reveal that the presence of adsorbing walls induces an increase in glass transition temperature, which counterbalances the asymmetry in the double well potential responsible for molecular motion.